Digital appliances, such as notebook or laptop computers, personal digital assistants (PDAs), or mobile phones, are commonly used with portable media, such as memory cards or USB drives. In some cases, secure data is stored on these portable media. The application responsible for securely transferring this data between the hosting appliance and the media often uses instructions that have a specific structure. As part of the transfer process, the host may cache the instruction; but as the host's operating system may unaware of the instruction's structure, and because the host's cache structure may not be compatible with the instruction's structure, the instruction, along with any associated data, may not be successfully transferred.